The present invention relates to flat panel display devices and methods of operating them and particularly to such display devices for displaying a color image.
Recently, a flat panel image display device has been developed having an envelope with front and rear walls in spaced parallel relationship separated by four sidewalls. Within the envelope and extending between the front and rear walls are a plurality of support vanes dividing the interior into a number of channels. On the interior of the front wall is a cathodoluminescent screen composed of a series of phosphor stripes. Within each channel is at least one electron beam guide for directing an electron beam down the channel from one end. The electron beam guides include means for deflecting the electron beam out of the guide at various points along the guide towards the cathodoluminescent screen. As in conventional display devices, a single frame of the image is composed of two interlaced fields. Each deflection point along the guides defines a line in one dimension, e.g., horizontal, in each field of the image to be displayed. One version of this display device known as an element scale tube uses a separate guide and beam for each color element in the line. To achieve field interlace in the newly developed display device, the beams may be alternately extracted from the guides at odd deflection points to form one field and then from the even points to form the other field of the frame. Alternately, each deflection point is used for two adjacent lines of the display image. During one field of the frame, the beams are deflected out of each point along the beam guides to the set of odd interlaced lines on the screen and during the second field of the frame and the beams at each deflection point are directed to the set of even screen lines. This deflection technique is described more fully in copending U.S. patent application Ser. No. 749,412 entitled "Flat Panel Display and Method of Operating the Same" filed on Dec. 10, 1976 by T. Credelle. In these devices, a separate beam guide and beam are utilized for each color element of the display and phosphor stripes extend longitudinally parallel to the beam guides.
Different approaches for color selection have been taken in other types of flat panel displays. One scheme is shown in U.S. Pat. No. 2,879,446 issued on Mar. 24, 1959 to W. R. Aiken in which an array of wires parallel to the screen serves as a form of shadow mask. By deflecting the electron beam toward the screen and between one pair of adjacent wires at different angles, a particular phosphor strip is excited. The Aiken device does not employ electron beam guides parallel to the screen as in the previously described prior art devices.